1. Field of the Invention
The present invention relates to a monomode optical source and an amplifying device continually tuneable in the near infra red.
2. Description of the Prior Art
In many applications: spectroscopy, characterization of optical components, etc. . . . ; it is necessary to have a variable wave length optical source of high brilliancy.
For constructing such a source, one of the techniques usually used is that of the non linear parametric oscillator which uses a pump wave produced by a laser and the order two non linear effect in a corresponding crystal, for example lithium niobate: LiNbO.sub.3. This type of source raises numerous problems such as those concerning the quality of the beam and the repeatability of the results.
Another possibility is that of using colored center lasers. This type of source has the disadvantage of requiring the frequent regeneration of the crystals used as active medium.
Finally, recently, multiwave length sources have been formed by using the Raman effect stimulated in the optical fibers. However, with this type of source, only a given number of possible wave lengths can be obtained, which wave lengths are fixed once and for all by the Raman diffusion process characteristic of the vibrational modes of the material used for forming the optical fiber.
One of the most important applications for optical fibers is the optical transmission of data, of digital or analog type. In this type of application, the optical fibers form the connecting channel between emitting members or sources and receiving members.
It is particularly important, especially for long distance optical connections, to reduce as much as possible the transmission losses. The origin of the losses is varied: nature of the optical fiber used, connection, etc. . . . For wide band and/or long distance connections, monomode optical fibers are used. The wave length used must also be taken into account. The lowest attenuation occurs for wave lengths centered about 1.5 .mu.m, i.e. in the near infra red range.
It is therefore advantageous to use radiation sources emitting at a wave length close to this value.
The aim of the invention is to respond to this need while overcoming the drawbacks of the prior art.